Feng Weiyi, Valiyaveettil Manojkumar, Dudiki Tejasvi, Mahabeleshwar Ganapati H, Andre Patrick, Podrez Eugene A, Byzova Tatiana V
Department of Molecular Cardiology, The Cleveland Clinic Foundation, Cleveland, 44195 OH USA.
The First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061 China.
Thromb J. 2017 Aug 30;15:22. doi: 10.1186/s12959-017-0145-1. eCollection 2017.
It is well accepted that functional activity of platelet integrin αβ is crucial for hemostasis and thrombosis. The β subunit of the complex undergoes tyrosine phosphorylation shown to be critical for outside-in integrin signaling and platelet clot retraction ex vivo. However, the role of this important signaling event in other aspects of prothrombotic platelet function is unknown.
Here, we assess the role of β tyrosine phosphorylation in platelet function regulation with a knock-in mouse strain, where two β cytoplasmic tyrosines are mutated to phenylalanine (DiYF). We employed platelet transfusion technique and intravital microscopy for observing the cellular events involved in specific steps of thrombus growth to investigate in detail the role of β tyrosine phosphorylation in arterial thrombosis in vivo
Upon injury, DiYF mice exhibited delayed arterial occlusion and unstable thrombus formation. The mean thrombus volume in DiYF mice formed on collagen was only 50% of that in WT. This effect was attributed to DiYF platelets but not to other blood cells and endothelium, which also carry these mutations. Transfusion of isolated DiYF but not WT platelets into irradiated WT mice resulted in reversal of the thrombotic phenotype and significantly prolonged blood vessel occlusion times. DiYF platelets exhibited reduced adhesion to collagen under in vitro shear conditions compared to WT platelets. Decreased platelet microparticle release after activation, both in vitro and in vivo, were observed in DiYF mice compared to WT mice.
β tyrosine phosphorylation of platelet αβ regulates both platelet pro-thrombotic activity and the formation of a stable platelet thrombus, as well as arterial microparticle release.
血小板整合素αβ的功能活性对于止血和血栓形成至关重要，这一点已被广泛接受。该复合物的β亚基会发生酪氨酸磷酸化，这对于体外由外向内的整合素信号传导和血小板凝块回缩至关重要。然而，这一重要信号事件在促血栓形成血小板功能的其他方面的作用尚不清楚。
在此，我们利用一种基因敲入小鼠品系评估β酪氨酸磷酸化在血小板功能调节中的作用，该品系中两个β细胞质酪氨酸被突变为苯丙氨酸（DiYF）。我们采用血小板输注技术和活体显微镜观察血栓形成特定步骤中涉及的细胞事件，以详细研究β酪氨酸磷酸化在体内动脉血栓形成中的作用。
受伤后，DiYF小鼠表现出动脉闭塞延迟和血栓形成不稳定。在胶原蛋白上形成的DiYF小鼠的平均血栓体积仅为野生型的50%。这种效应归因于DiYF血小板，而非携带这些突变的其他血细胞和内皮细胞。将分离的DiYF血小板而非野生型血小板输注到受辐照的野生型小鼠中，导致血栓形成表型逆转，并显著延长血管闭塞时间。与野生型血小板相比，DiYF血小板在体外剪切条件下对胶原蛋白的粘附减少。与野生型小鼠相比，DiYF小鼠在体外和体内激活后血小板微粒释放均减少。
血小板αβ的β酪氨酸磷酸化调节血小板的促血栓形成活性、稳定血小板血栓的形成以及动脉微粒释放。
